#!/bin/bash
echo "cmd: (1)date (2)ls (3)pwd"

while :
do
	read -p "please input your cmd: (1-4) " n
	case $n in
		1)
			date
			break
			;;
		2)
			ls -l
			break
			;;
		3)
			pwd
			break
			;;
		*)
			echo "usage:please input (1-4)"
			break
	esac


done


